It is generally accepted that chronic stress impairs female reproduction. It negatively affects ovarian function and the number of ovulated oocytes. Chronic stress lowers the number of retrieved oocytes. Ovarian follicular development is regulated by both pituitary-derived gonadotropins and intraovarian regulatory factors. The main corticosteroids are cortisol, cortisone, 11-deoxycortisol and corticosterone, cortisol being one of the most commonly used welfare and stress physiological indicator. In this study, we investigated the effect of cortisol level on progesterone patterns and ovulation in the dog. Cortisol and progesterone level of serum were analyzed by radioimmunoassay. The day of ovulation was considered as the day when serum progesterone concentration was 6.0∼8.0 ng/ml. In vivo dog oocytes were collected by flushing oviducts of mixed-breed bitches at three days after ovulation. We classified dogs as having group 1 (cortisol level, 0 ≤ or < 2 μg/dl), group 2 (corisol level, 2 ≤ or < 4 μg/dl), group 3 (cortisol level, 4 ≤ or < 6 μg/dl) and group 4 (cortisol level, 6 μg/dL ≤). The patterns of progesterone were not different in four cortisol groups. The average numbers of retrieved oocytes was not different in four cortisol groups. These results suggest that different cortisol levels on estrus dogs do not affect ovulation, number of ovulated oocytes and progesterone changes.

본 연구는 한우 체세포를 이용하여 생산된 복제란을 한우 대리모에 이식하여 임신이 확인된 개체에서 임신 기간 중 주요 호르몬의 발현 특성을 인공수정으로 임신된 대리모와 비교 분석하고자 실시하였다. 한우 섬유아세포를 이용하여 생산된 체세포 복제란을 자연발정으로 동기화된 한우 대리모에 이식하여 임신이 확인된 개체를 공시하였으며(n=8), 대조군으로는 인공수정으로 임신된 대리모을 사용하였다(n=5). 발정 관찰 후 60일경에 직장검사로 임신을 확인하였다. 주요 스테로이드 호르몬인 progesterone(P4)와 estradiol-l7 (E2) 농도는 방사선동위원소 면역분석시험(RIA) 방법을 이용하였으며, 혈중 cortisol 농도는 ELISA 방법으로 측정하였다. 인공수정한 대리모의 경우 E2 농도가 분만 시기에 급격하게 증가하였으나, P4 농도는 분만 시기에 급격하게 감소하는 경향을 나타내었다. 이에 반해 복제란 이식우의 혈장 P4 농도는 분만 50일 전부터 분만 10일전까지는 대조군과 유사하게 유지되었으나, 분만예정일에는 전혀 떨어지지 않고 높은 수준으로 유지되었다. 한편, 복제란 이식우에서 분만 때까지 정상적으로 임신이 유지된 대리모들의 경우는 임신 기간 동안 cortisol 농도는 임신 후반기까지 낮게 유지되며 별다른 변화를 나타내지 않았다. 반면에 유산이 일어난 개체의 경우에는 임신 100일경에 cortisol의 농도가 급격하게 증가하는 것을 확인하였다. 이상의 결과를 종합하여 보면, 복제란 이식우의 경우 분만예정일 전 후에 일어나는 급격한 호르몬의 변화가 일어나지 않음을 확인할 수 있었으며, 이러한 현상은 복제란 이식우의 분만 지연과 밀접한 관계가 있는 것으로 사료된다.

The ovaries of 178 Holstein heifers or cows (heifer; 41, 1 parity; 72, 2 parity; 65) on Day 6 or 7 (Day 0=day of estrus) were examined by transrectal ultrasonography. Diameter of corpus luteum (CL) and large follicle ( 10 mm), and luteal tissue area were determined by ultrasound system with a 5 MHB rectal probe. Blood samples were taken to progesterone analysis. After selection of recipients, frozen Holstein embryos were thawed and directly transferred to recipients non-surgically. The diameter of CL and luteal tissue area was greater (P<0.01) on Day 7 than on Day 6 in heifers, 1 parity or 2 parity cows, respectively, although progesterone concentrations were not different. The presence of fluid-filled luteal cavitied or multiple CL (2 or more) did not affect serum progesterone concentration. A large follicles were observed in 67.4% of heifers or cows and the average diameter was 14.1 mm. Greater luteal tissue area attributed higher pregnancy in heifers, but not in cows, although there were no difference on pregnancy rate according to progesterone concentration in heifers or cows. The pregnancy rate of recipients contained a large follicle at embryo transfer was lower than that of recipients not contained. These results show ultrasonic assessment of ovaries in Holstein recipients is a reliable tool to determine the follicle and CL for recipient selection.

Plasma progesterone concentrations were measured by using radjoimmunoassay for early diagnosis of pregnancy in Cheju-native mares. A total of 226 pony mares were examined for pregnancy during breeding and non breeding seasons. Plasma progesterone levels 20~23 days after the onset of oestrus were 4.67+O.67ng /rnl and O.55+O.O4ng /ml for mares becornrning pregnant and not pregnant after the estrus, respectively, and there was a significant differences (p<0.01) between the two groups. Progesterone concentration of pregnant mares gradually increased in 30 days andreached a peak (10.3ng /ml) during the third month of gestation. However, the concentration decresed to the base line (1.llng /rnl) at 7 months and gradually increased again as foaling approached (2.lng /ml). Early diagnosis for pregnancy of Cheju mares by progesterone level at 20~23 days after onset of oestrus was 88% accurate when 4.6ng /ml was used to classify mares as pregnancy and below 1.3ng /rnl was used to determine nonpregnant mares. However, the accuracy of the diagnosis was improved to 96% when a progesterone level of above 2ng /mi was used to classify mares for pregnancy. Diagnosis for pregnancy was 69.6% accurate when mares were classified as pregnancy by horse owners during breeding season. The progesterone levels of pregnant and non-pregnant mares during non-breeding season varied greatly between individual animals, Plasma progesterone levels of pregnant animals ranged from 3.5ng /mi to above 6.2ng /mi whereas similar values were observed in non-pregnant animals. Radioirnrnunoassay technicjues can be applied for the early pregnant diagnosis of Cheju native mares when progesterone levels are measured during the early gestation period (18~23 days after onset of oestrus). However, progesterone concentration of mares in non-breeding season is conisidered unsuitable as a indicator of pregnant diagnosis.